Rigging is the method of handling materials using
fiber line, wire rope, and associated equipment. Fiber
line and wire rope were discussed in chapters 4 and 5.
We will now discuss how these materials and
equipment can be used in various tackle and lever
arrangements to form the fundamental rigging
necessary to move heavy loads. Additionally, we
discuss the makeup of block and tackle, reeving
and common types of tackle
arrangements. Information is also provided on other
common types of weight-handling devices, such as
slings, spreaders, pallets, jacks, planks and rollers,
blocking and cribbing, and scaffolds.
SAFETY is paramount in importance. You will be
briefed throughout this chapter on safety measures to
be observed as it pertains to the various operations or
particular equipment we are discussing. Also,
formulas are given for your use in calculating the
working loads of various weight-moving devices,
such as hooks, shackles, chains, and so on. SAFE
rigging is the critical link in the weight-handling
BLOCK AND TACKLE
The most commonly used mechanical device is
block and tackle. A block (fig. 6-1) consists of one or
more sheaves fitted in a wood or metal frame
supported by a shackle inserted in the strap of the
Figure 6-1.Parts of a fiber line block.
block. A tackle is an assembly of blocks and lines used
to gain a mechanical advantage in lifting and pulling.
The mechanical advantage of a machine is the
amount the machine can multiply the force used to lift
or move a load. The strength of an individual
determines the weight he or she can push or pull. The
ability to push or pull is referred to as the amount of
force the individual can exert. To move any load
heavier than the force you can exert requires the use
of a machine that can provide a mechanical advantage
to multiply the force you can apply. If you use a
machine that can produce a push or pull on an object
that is 10 times greater than the force you apply, the
machine has a mechanical advantage of 10. For
example, if the downward pull on a block-and-tackle
assembly requires 10 pounds of force to raise 100
pounds, the assembly has a mechanical advantage of
In a tackle assembly, the line is reeved over the
sheaves of blocks. The two types of tackle systems are
simple and compound. A simple tackle system is an
assembly of blocks in which a single line is used (fig.
6-2, view A). A compound tackle system is an
assembly of blocks in which more than one line is used
(fig. 6-2, view B).
Figure 6-2.Tackles: A. Simple tackle; B. Compound tackle.